1. Field of the Invention
This invention relates to an array-type light receiving device, and more particularly to an array-type light receiving device and a light collection method with improved light receiving efficiency.
2. Background Art
Recently, with the increasing resolution of digital cameras and mobile phone-mounted cameras, downscaling of array-type light receiving devices mounted thereon has been in progress. However, the pixel pitch of the light receiving device is narrowed with downscaling. Hence, unfortunately, incident light entering the lens cannot be efficiently guided to the light receiving section.
Conventionally, a light collector having a spherical shape is used for an array-type light receiving device. However, although the light collector having only a spherical shape has an effect of allowing light perpendicularly incident on the array-type light receiving device to be efficiently guided to the light receiving section, it has little effect of allowing obliquely incident light to be efficiently guided to the light receiving section.
For example, when light is incident on an array-type light receiving device from a camera lens, the component of perpendicularly incident light is intense at the center of the array-type light receiving device, and the component of obliquely incident light is intense at the periphery of the array-type light receiving device. The obliquely incident light impinges on interconnection in the device and may fail to reach the light receiving section in the device, resulting in decreasing the light receiving sensitivity at the periphery. Thus, in two-dimensionally arrayed devices, the light receiving efficiency is high at the center, but low at the periphery, producing a sensitivity difference (shading) therebetween. Furthermore, unless obliquely incident light is delivered to the light receiving section of the device using a light collector, it enters the light receiving section of an adjacent pixel and causes color mottling.
To solve the problem of shading, JP-A 2006-324439(Kokai) discloses a technique of shifting the center of the light receiving section with the distance from the center of the arrayed devices. Although this technique can prevent shading, the manufacturing process is complicated because each pixel has a different structure.
JP-A 2006-229004(Kokai) discloses a technique of gradually increasing the opening diameter of the top interconnect of multilayer interconnection with the distance from the center of the arrayed devices. Although this technique can prevent shading, the manufacturing process is complicated because each pixel has a different structure.
JP-A 2006-114592(Kokai) discloses a technique of using a spherical shape for a first light collector and a second collector, in which the shape is varied for each pixel. Although this technique can prevent shading and color mottling, the spherical shape alone cannot sufficiently increase the efficiency of receiving obliquely incident light, and the manufacturing process is complicated because each pixel has a different structure.